All Black and Crusaders player Ali Williams, who is often seen as a villain on and off the field, is being hailed as a hero after breaking up a fight in Christchurch on the weekend.

Williams and a couple of team mates were out on the town after the Hurricanes game when trouble broke out.

"There was this group of 20 to 25 year olds all arguing... Then all of a sudden a brawl just started between about six people and then Ali Williams rushed up and saved the day," says eye witness Max Rooney.

The big lock, no stranger to off-field misbehaviour himself, is shown getting in amongst a group of five or six brawling young men, and stopping the fight.

All the action was captured on camera phone and released on ONE News evening edition.